He was promoted to major in September 1914 and to lieutenant colonel in July 1918, while still in Europe, and he stayed on as a member of the Japanese delegation to the Versailles Peace Treaty negotiations in February 1919.

In July 1940, Hata had a pivotal role in bringing down the Yonai cabinet by resigning his post as Minister of War.

Hata was promoted to the rank of Field Marshal (Gensui) on June 2, 1944 following Japanese victory at Operation Ichi-Go.

Hata was requested to take command of the Second General Army, based in Hiroshima from 1944 to 1945 in preparation for the anticipated Allied invasion of the Japanese home islands.

Hata was one of the senior generals who agreed with the decision to surrender, but asked that he be stripped of his title of Field Marshal in atonement for the Army's failures in the war.

In 1948, as a result of the International Military Tribunal for the Far East, he was sentenced to life imprisonment under the charges of: “Conspiracy, waging aggressive war, disregarding his duty to prevent atrocities”.